In many situations it can be desirable to image the interior of opaque objects. By way of example but not limitation, in the medical field, it can be desirable to image the interior of a patient's body so as to allow viewing of internal structures without physically penetrating the skin.
Computerized Tomography (CT) has emerged as a key imaging modality in the medical field. CT imaging systems generally operate by directing X-rays into the body from a variety of positions, detecting the X-rays passing through the body, and then processing the detected X-rays so as to build a three-dimensional (3D) data set of the patient's anatomy. This 3D data set can then be processed so as to create a 3D computer model of the patient's anatomy. The 3D data set and 3D computer model can then be visualized so as to provide images (e.g., slice images, 3D computer images, etc.) of the patient's anatomy.
By way of example but not limitation, and looking now at FIGS. 1 and 2, there is shown an exemplary CT imaging system 5. CT imaging system 5 generally comprises a torus 10 which is supported by a base 15. A center opening 20 is formed in torus 10. Center opening 20 receives the patient anatomy which is to be scanned.
Looking next at FIG. 3, torus 10 generally comprises a fixed gantry 22, a rotating disc 23, an X-ray tube assembly 25 and an X-ray detector assembly 30. More particularly, fixed gantry 22 is disposed concentrically about center opening 20. Rotating disc 23 is rotatably mounted to fixed gantry 22. X-ray tube assembly 25 and X-ray detector assembly 30 are mounted to rotating disc 23 in diametrically-opposing relation, such that an X-ray beam 40 (generated by X-ray tube assembly 25 and detected by X-ray detector assembly 30) is passed through the patient anatomy disposed in center opening 20. Inasmuch as X-ray tube assembly 25 and X-ray detector assembly 30 are mounted on rotating disc 23 so that they are rotated concentrically about center opening 20, X-ray beam 40 will be passed through the patient's anatomy along a full range of radial positions, so as to enable CT imaging system 5 to create a “slice” image of the anatomy penetrated by the X-ray beam. Furthermore, by moving the patient and CT imaging system 5 relative to one another during scanning, a series of slice images can be acquired, and thereafter appropriately processed, so as to create a 3D data set of the scanned anatomy. This 3D data set can then be processed so as to create a 3D computer model of the scanned anatomy. In practice, it is common to configure X-ray detector assembly 30 so that multiple slices of images (e.g., 8 slices, 16 slices, 32 slices, etc.) may be acquired with each rotation of rotating disc 23, whereby to speed up the acquisition of scan data.
In practice, it is now common to effect helical scanning of the patient's anatomy so as to generate a 3D data set of the scanned anatomy, which can then be processed so as to create a 3D computer model of the scanned anatomy. The 3D data set and 3D computer model can then be visualized so as to provide images (e.g., slice images, 3D computer images, etc.) of the patient's anatomy.
The various electronic hardware and software for controlling the operation of rotating disc 23, X-ray tube assembly 25 and X-ray detector assembly 30, as well as for processing the acquired scan data so as to generate the desired slice images, 3D data set and 3D computer model, may be of the sort well known in the art and may be located in torus 10 and/or base 15.
In many cases CT imaging system 5 is intended to be stationary, in which case base 15 of CT imaging system 5 is set in a fixed position on the floor of a room and a special motorized bed is provided to move the patient relative to CT imaging system 5 during scanning. More particularly, with a stationary CT imaging system 5, the patient is brought to the location of CT imaging system 5, the patient is placed on the special motorized bed, and then the motorized bed is used to move the patient relative to CT imaging system 5 (i.e., to advance the patient into center opening 20 of CT imaging system 5) so that some or all of the length of the patient may be scanned by CT imaging system 5.
In other cases CT imaging system 5 is intended to be mobile so that the CT imaging system may be brought to the patient and the patient scanned at the patient's current location, with the CT imaging system moving relative to the patient during scanning. Scanning the patient with a mobile CT imaging system 5 can be highly advantageous, since it can reduce delays in patient scanning (e.g., the patient can be scanned in an emergency room rather than waiting to be transported to the radiology department) and/or it can allow the patient to be scanned without requiring movement of the patient (e.g., the patient can be scanned at their bedside in an intensive care unit, “ICU”).
To this end, and looking now at FIGS. 4 and 5, base 15 may comprise a transport assembly 50 for (i) moving mobile CT imaging system 5 to the location of the patient prior to scanning, and (ii) moving the CT imaging system relative to the patient during scanning. More particularly, transport assembly 50 preferably comprises (i) a gross movement mechanism 55 for moving CT imaging system 5 relatively quickly across room distances, so that the CT imaging system can be quickly and easily brought to the bedside of the patient, such that the patient can be scanned at their bedside without needing to be moved to a radiology department, and (ii) a fine movement mechanism 60 for moving the CT imaging system precisely, relative to the patient, during scanning so that the patient can be scanned on their bed or gurney without needing to be moved onto a special motorized bed.
In one preferred form of the invention, gross movement mechanism 55 preferably comprises a plurality of free-rolling casters 62, and fine movement mechanism 60 preferably comprises a plurality of centipede belt drives 63 (which can be configured for either stepped or continuous motion, whereby to provide either stepped or continuous scanning of the patient). Hydraulic apparatus 65 permits either gross movement mechanism 55 or fine movement mechanism 60 to be engaged with the floor, whereby to facilitate appropriate movement of mobile CT imaging system 5.
Thus, with a mobile CT imaging system 5, the mobile CT imaging system may be pre-positioned in an “out of the way” location (e.g., in an unused corner of an emergency room) and then, when a patient requires scanning, the patient may be quickly and easily scanned at their bedside, by simply moving the mobile CT imaging system to the patient's bedside on gross movement mechanism 55 (e.g., on casters 62), and thereafter moving the mobile CT imaging system during scanning on fine movement mechanism 60 (e.g., on centipede belt drives 63).
However, it has been found that where the mobile CT imaging system becomes larger (e.g., such as where the mobile CT imaging system is sized for full-body scans), using free-rolling castors 62 for gross movement mechanism 55 can become problematic. By way of example but not limitation, where the mobile CT imaging system is sized for full-body scans, the mobile CT imaging system can weigh thousands of pounds and it can require substantial effort to physically push the mobile CT imaging system down corridors and across rooms when the mobile CT imaging system is supported on free-rolling castors. Furthermore, where the mobile CT imaging system is sized for full-body scans, it can be difficult to maneuver the mobile CT imaging system when it is supported on free-rolling castors, e.g., such as when the mobile CT imaging system must be maneuvered around a corner in a hospital corridor.
In addition to the foregoing, it has also been found that where the floor of the medical facility has substantial irregularities (e.g., bumps, recesses, etc.), centipede belt drives 63 of mobile CT imaging system 5 may not uniformly contact the floor over the complete “stroke” of the scan. When this occurs, mobile CT imaging system 5 may not move uniformly over the full stroke of the scan, which can affect the accuracy of the scan results.
Among other things, mobile CT imaging system 5 may shift (i.e., “drift”) laterally during its scan stroke, then shift further laterally during its return stroke, then shift further laterally during its next scan stroke, then shift further laterally during its next return stroke, etc.
Over long scan strokes (e.g., such as is the case with “full body” scans), and/or with repeated scan strokes (e.g., such as is the case where numerous scans must be taken), such lateral “walking” (or “drifting”) of CT imaging system 5 may create issues with scan quality.
Furthermore, since CT imaging system 5 is moving independently of the bed or gurney which is supporting the patient, there is also the possibility that, after repeated long scan strokes, CT imaging system 5 may walk (or drift) so far laterally that the CT imaging system bumps into the bed or gurney which is supporting the patient.
Thus, there is a need for a new and improved movement system for a mobile CT imaging system which can facilitate movement and maneuvering of the mobile CT imaging system when moving the mobile CT imaging system between scanning locations, and which can substantially eliminate lateral walk (or drift) over the complete stroke of a scan during scanning, even when the floor includes substantial irregularities, whereby to improve the accuracy of the scan results and avoid unintentional engagement of the CT imaging system with the bed or gurney which is supporting the patient.